1. Field of the Invention
The present invention relates to an oil-cooled type screw compressor in which at least a discharge port-side portion of a compressor body is positioned within a casing with an oil separating element received therein.
2. Description of the Prior Art
Heretofore, such an oil-cooled type screw compressor as shown in FIG. 2 has publicly been known. In this known compressor, a motor 42 as drive means for screw rotors 41 has a shaft 43 in common with one screw rotor 41, and a body casing 44 which houses the screw rotors 41 therein and a motor casing 45 of the motor 42 are formed integrally with each other (Japanese Patent Laid Open No. 184984/85). In FIG. 2, gas is sucked in through a suction port 46 formed in the left end face of the motor casing 45, then passes through a clearance formed between a stator and a rotor of the motor 42, then is compressed by the screw rotors 41 while being oiled, and passes through an oil separating element 47 for the separation of oil from the gas. The thus-compressed gas is discharged from a discharge port 48 formed in a right upper position of the casing 44 in FIG. 2. On the other hand, the oil separated from the compressed gas by the oil separating element 47 is once stored in an oil sump 49.
In the above known compressor, the oil discharged together with the compressed gas from the screw rotors 41 is captured by the oil separating element 47 and gradually stays in the same element, as indicated with cross hatching in FIG. 2. As a result, the portion of the oil separating element 47 through which the compressed gas can pass becomes narrower gradually, thus giving rise to the problem that the oil separating efficiency is deteriorated.